An astronaut with four space shuttle missions has retired from NASA. Steven L. Smith left the agency after a career that began even before he became an astronaut.

"Steve brought so much to NASA during the course of his career," said Pat Forrester, chief of the Astronaut Office at NASA's Johnson Space Center. "He made great contributions not just to the astronaut office and the Johnson Space Center but to the entire agency. We appreciate his service over the past several decades and wish him well in the future."

Smith was selected as an astronaut in 1992, after first coming to NASA in 1989 as a payload officer in the Mission Operations Directorate. He was the first member of the 1992 class to receive a flight assignment and made his first of four spaceflights in 1994 as part of Endeavour's STS-68 mission, conducting Earth observations with the Space Radar Laboratory.

Smith flew again aboard Discovery in 1997, as part of the STS-82 crew, visiting the Hubble Space Telescope and performing three of the mission's four spacewalks. He returned to Hubble and served as the payload commander in 1999 as part of the STS-103 mission, again onboard Discovery, and performed two more spacewalks.

Smith's final flight came in 2002, on board space shuttle Atlantis for STS-110. Visiting the new International Space Station, he served as the lead spacewalker, performing two more spacewalks and helping to install the station's initial truss segment.

During those four missions, Smith conducted seven spacewalks, totaling 49 hours and 25 minutes. He currently ranks seventh on the list of most time spent spacewalking by U.S. astronauts.

Following his final spaceflight, Smith continued to serve in a variety of positions at NASA, such as the Automated Transfer Vehicle (ATV) Launch Package Manager for all five ATV flights, the International Space Station Program's liaison to the European Space Agency, and associate director for the program's science directorate at NASA's Ames Research Center in California.

Smith was born in Phoenix, Arizona, and considers San Jose, California, his hometown. He earned a bachelor's degree in electrical engineering, and two master's degrees in electrical engineering and business administration, all from Stanford University.